Human faces are compelling visual objects whose salience is further boosted when they portray strong emotional expressions such as anger. Can aftereffects associated with adaptation to facial expressions (FEAs) be induced when observers are unaware of those expressions under continuous flash suppression (CFS)? During repeated 5-second adaptation periods, observers monocularly viewed faces that were either visible continuously or were erased from visual awareness by a CFS stimulus presented to the other eye. During brief test trials interspersed between successive adaptation periods, observers were presented with a “morph” face whose emotional expression was the weighted average between two extremes of expression used to create the morph (e.g., angry vs fearful); following each test presentation, observers selected one of two response categories to indicate perception of the test face's emotional expression. In two experiments we found that robust FEAs were generated when adapting faces were visible but were abolished when those faces were perceptually suppressed by CFS; these findings replicate earlier results measuring face identity and gender aftereffects. A third experiment using the same stimuli and procedures produced significant contrast adaptation aftereffects to suppressed faces, confirming that the adapting stimuli were not rendered completely ineffective by CFS. In a fourth experiment, observers performed a luminance discrimination task that required attending to the spatial location of an adapting face, although the face itself could not be seen. In the presence of endogenous attention, significant FEAs were induced by suppressed adapting faces. These findings, together with other evidence, suggest that attentional resources must be available and further allocated to the location of the face stimulus for adaptation aftereffects to occur, even when the face is outside observers' awareness.